Influent water treatment is needed to remove contaminants from raw water to make it suitable for potable or industrial uses. These contaminants may be either soluble or insoluble, with solubility dictating the procedure needed for proper removal.
Soluble components are usually removed or minimized via lime/soda softening, demineralization, etc. Insoluble components may be reduced or removed by settling or filtration.
Swamps and wetlands often introduce color contaminants into raw water sources. The problem is particularly acute after heavy rainfalls. Color in raw water causes various problems including objectionable taste, increased bacteria and algae growth, fouling of anion exchange resins, interference with coagulation, and stabilization of soluble iron and manganese.
Most color in raw water is colloidal in nature and results from organic material such as humic acids, lignins, tannins, fulvic acids, and other related compounds that are leached from leaves or other vegetation.
I have found that such color contamination can be effectively reduced by the use of a combination of powdered activated carbon (PAC) and a water soluble or water dispersible cationic polyelectrolyte. In one particularly unique aspect of the invention, a slurry of P.A.C. comprising an effective polysaccharide suspending agent is added to the influent water. The requisite cationic polymer or polymers are added separately from the P.A.C. containing slurry.